1. Field of the Invention
This invention relates to new compounds comprising dithiophosphorylated copolymers of aziridineethyl acrylates or methacrylates/alkyl acrylates or alkyl methacrylates and to the preparation of such compositions. These dithiophosphorylated aziridineethyl acrylate or methacrylate/alkyl acrylate or alkyl methacrylate copolymers are suitable for use as metal-free, anti-wear agents in lubricating oil compositions. The copending application of Pellegrini et al entitled Lubricating Oils Containing Dithiophosphorylated Copolymers of Aziridineethyl Acrylate or Methacrylate and Alkyl Acrylate or Alkyl Methacrylate, Ser. No. 843,315, filed Oct. 18, 1977, describes lubricating oil compositions suitable for use in combination with the dithiophosphorylated copolymers disclosed herein the disclosure of which is incorporated herein by reference.
2. Description of The Prior Art
The monomeric aziridinylethyl carboxylic acid esters from which the copolymers in the present invention are prepared are known. For example, the preparation of aziridineethyl methacrylate and aziridineethyl acrylate is described in U.S. Pat. No. 3,338,885 issued to Coker et al. on Aug. 29, 1967, which discloses the preparation of 2-(1-aziridinyl) ethyl methacrylate by heating dried methyl methacrylate with N-(2-hydroxyethyl) aziridine in the presence of N,N'-diphenyl-p-phenylenediamine as a polymerization inhibitor. The mixture is heated and small pieces of sodium are added. The product is next cooled, filtered and distilled. A distillation cut obtained at 111.2.degree. F. (44.degree. C.) at 0.1 mm of Hg comprises 2-(1-aziridinyl)ethyl methacrylate.
The monomeric C.sub.8 -C.sub.18 alkyl esters of acrylic and methacrylic acid are also known and disclosed, for example, in U.S. Pat. No. 3,864,099, issued to Ek on Feb. 4, 1975. Monomeric C.sub.8 -C.sub.18 alkyl esters of acrylic or methacrylic acid are described as particularly suitable for copolymerizing with aziridineethyl acrylate or methacrylate using conventional techniques in the art.
Similarly, dithiophosphoric acid esters and their derivatives are known and described, for example, in U.S. Pat. No. 3,826,745 issued to Ryer et al. on July 30, 1974, which teaches dithiophosphoric acid ester derivatives in combination with amine salts of mixed acid phosphates as antiwear, corrosion inhibitors and anti-oxidant additives for lubricating oils. These dithiophosphates are additionally described as suitable for use in any type lubricating oil compositions, including animal and vegetable oils as well as mineral lubricating oils and synthetic oils.
U.S. Pat. No. 3,865,740 issued to Goldschmidt on Feb. 11, 1975, describes certain alkyl, aryl, alkaryl or arylalkyl 0,0'-diesters of dithiophosphoric acid which may serve as extreme pressure agents, antioxidants and ashless dispersants for lubrication oil compositions.
It must be noted, however, that the specific dialkyl, diaryl, dialkaryl, diarylalkyl, or diaryloxyalkyl dithiophosphorylated copolymers claimed herein are new.